<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html lang="en">
<head>
    <meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
    <title>Document</title>
    <style type="text/css">
        .parent{
            display: flex;
            width: 80%;
            height: 200px;
            background-color: aliceblue;
            flex-direction: row;
        }

        .parent div{
            width: 100px;
            height: 100px;
            background-color: cornflowerblue;
        }

        .parent div:nth-child(3){
            /*设置自己在侧轴的排列方式*/
            align-self: flex-end;
        }
    </style>
</head>
<body>
    <div class="parent">
        <div>1</div>
        <div>2</div>
        <div>3</div>
    </div>
</body>
</html>